DWT filter bank time-domain scaling functions
Create a seven-level DWT filter bank for a length 2048 signal, using the Daubechies
db2 wavelet and a sampling frequency of 1 kHz.
wv = "db2"; len = 2048; Fs = 1e3; lev = 7; fb = dwtfilterbank('SignalLength',len,'Wavelet',wv,'Level',lev,'SamplingFrequency',Fs);
Plot the scaling functions for each level of the filter bank.
[phi,t] = scalingfunctions(fb); plot(t,phi') grid on xlim([-len/2*1e-3 len/2*1e-3]) title('Scaling Functions') legend('A1','A2','A3','A4','A5','A6','A7')
phi— Time-centered scaling functions
Time-centered scaling functions of the filter bank
fb, returned as a real-valued
L-by-N matrix, where
L is the filter bank
N is the
SignalLength. The scaling
functions are ordered in
phi from the finest scale
resolution to the coarsest scale resolution.
t— Sampling instants
Sampling instants, returned as a real-valued vector
of length N, where N is the filter
SignalLength. Sampling instants lie in the interval , where DT is the filter bank sampling
period (reciprocal of the filter bank sampling frequency).